b:head_first_statistics:calculating_probability
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b:head_first_statistics:calculating_probability [2020/09/29 14:59] – hkimscil | b:head_first_statistics:calculating_probability [2023/09/26 20:06] (current) – [Dependent and Independent event] hkimscil | ||
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A = event A | A = event A | ||
- | [{{: | + | [{{: |
<WRAP clear /> | <WRAP clear /> | ||
- | [{{: | + | [{{: |
<WRAP clear /> | <WRAP clear /> | ||
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[{{: | [{{: | ||
<WRAP clear /> | <WRAP clear /> | ||
- | [{{: | + | [{{: |
* Intersection $ \cap $ | * Intersection $ \cap $ | ||
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- | [{{: | + | [{{: |
- | [{{: | + | [{{: |
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< | < | ||
- | [{{: | + | [{{: |
- | [{{: | + | [{{: |
<WRAP clear /> | <WRAP clear /> | ||
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* P(Coffee) | * P(Coffee) | ||
* P(Donuts | Coffee) | * P(Donuts | Coffee) | ||
+ | < | ||
+ | d (3/4) -- c [x = 3/5] [k = p(c and d)] | ||
+ | -- ~c [y = 2/5] | ||
+ | ~d (1/4) -- c (1/3) --> [a = p(c and ~d)] | ||
+ | -- ~c [2/3] | ||
+ | |||
+ | x * 3/4 = p(d and c) = 9/20 | ||
+ | x = 9/20 * 4/3 | ||
+ | = 36/60 | ||
+ | = 6/10 = 3/5 | ||
+ | |||
+ | P(~d ∩ c) = a = 1/4 * 1/3 = 1/12 | ||
+ | P(c) = k + a | ||
+ | k = 3/4 * 3/5 = 9/20 | ||
+ | a = 1/12 | ||
+ | P(c) = 54/120 + 10/120 = 64/120 = 16/30 = 8/15 | ||
+ | |||
+ | c (8/15) -- d [j] | ||
+ | -- ~d | ||
+ | ~c (7/ | ||
+ | j = p(d | c) | ||
+ | p(d and c) = 9/20 이므로 | ||
+ | 8/15 * j = 9/20 | ||
+ | j = 9/20 * 15/8 = 9/4 * 3/8 = 27/32 | ||
+ | </ | ||
+ | |||
+ | |||
</ | </ | ||
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Step 1: Finding P(Black ∩ Even) | Step 1: Finding P(Black ∩ Even) | ||
+ | \begin{eqnarray*} | ||
+ | P(Black \cap Even) | ||
+ | & = & \frac {18}{38} * \frac {10}{18} \\ | ||
+ | & = & \frac {10}{38} \\ | ||
+ | P(Black \vert Even) & = & \frac {P(Black \cap Even)}{P(Even)} \\ | ||
+ | P(Black \cap Even) & = & P(Black) * P(Even \vert Black) \\ | ||
+ | P(Black \vert Even) & = & \frac{P(Black) * P(Even \vert Black)} {P(Even)} | ||
+ | \end{eqnarray*} | ||
- | $$ {P(Black \cap Even) = \frac{18}{38} * \frac{10}{18} = \frac{10}{38} $$ | ||
- | $$ P(Black \vert Even) = \frac {P(Black \cap Even)}{P(Even)} $$ | ||
- | |||
- | $$ P(Black \cap Even) = P(Black) * P(Even \vert Black)$$ | ||
- | |||
- | $$ P(Black \vert Even) = \frac{P(Black) * P(Even \vert Black)} {P(Even)} $$ | ||
Step 2: Finding P(Even) | Step 2: Finding P(Even) | ||
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$$P(A \vert B) = \frac {P(A) * P(B \vert A)}{P(A) * P(B \vert A) + P(A') * P(B \vert A')} $$ | $$P(A \vert B) = \frac {P(A) * P(B \vert A)}{P(A) * P(B \vert A) + P(A') * P(B \vert A')} $$ | ||
- | This is called "< | + | |
+ | This is called "< | ||
====== e.g. ====== | ====== e.g. ====== | ||
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* The probability of the ball having landed in a pocket with a number greater than 4 given that it’s red. | * The probability of the ball having landed in a pocket with a number greater than 4 given that it’s red. | ||
* The probability of the ball landing in pockets 1, 2, 3, or 4. | * The probability of the ball landing in pockets 1, 2, 3, or 4. | ||
- | |||
</ | </ | ||
+ | https:// | ||
+ | https:// | ||
+ | https:// | ||
+ | https:// | ||
- | + | {{: | |
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + |
b/head_first_statistics/calculating_probability.1601359188.txt.gz · Last modified: 2020/09/29 14:59 by hkimscil